The present invention relates to an electromagnetic actuating apparatus according to the preamble of the main claim. An apparatus of this kind is known from DE 102 40 774 by the same applicant and is used for various actuating tasks, for example in conjunction with internal combustion engines.
FIG. 5, relating to the prior art, shows the structural design of an electromagnetic actuating apparatus which is assumed to be known. A stationary core unit 32 is provided in a cylindrical housing 30, with a coil former 34 with a winding 36 provided thereon being located radially between said stationary core unit and cylindrical housing. An armature unit, which has an elongate tappet unit 42 which forms an engagement end 44 at its end, is guided such that it can move axially in relation to the core unit 32. The armature unit has, opposite the engagement end 44 and for the purpose of magnetically interacting with the core unit, a multiple-disk arrangement comprising a permanent-magnet disk 38 and also, adjacent to this on either side, a first and, respectively, a second armature disk 48, 50. The casing of this arrangement is enclosed by a surrounding ring 52.
In the position shown in FIG. 5, the armature unit is attached to the core 32 by the action of the permanent magnet 38. Applying current to the winding 36 then generates a repelling field, as a result of which the armature unit (on the right in the plane of the figure) is moved axially and, accordingly, an actuating partner can be driven such that the end acts on the engagement end 44.
A schematically described apparatus of this kind is known in various embodiments and is used for various applications, for example including for camshaft adjustment in an internal combustion engine. In this case, the ease of manufacture makes it highly suitable for large-scale production, and therefore the technology known from the prior art can already be produced at favorable unit costs.
However, at the same time, the technology illustrated in accordance with FIG. 5 has also proven inflexible, in particular in respect of special installation space requirements. For example, it is, as shown in FIG. 5, a specific structural principle of the known technology for the tappet unit 42 to be part of the armature unit and therefore to be arranged rigidly on the disk pack 48, 38, 50; these units cannot be separated and, for efficient installation, therefore require a radially symmetrical installation contour which corresponds as far as possible. FIG. 6, as a schematic installation contour in an internal combustion engine (specifically: the installation space for an electromagnetic actuator for camshaft adjustment), shows, in contrast, by way of example, the real space conditions at the site of use; the assembly (shown only symbolically in FIG. 7) shows that a traditional radially symmetrical arrangement in accordance with FIG. 5 (inasmuch as the unit 60 shows an actuator, which can be mounted, in accordance with the principle of FIG. 5) cannot be installed with the installation conditions of FIG. 6. Rather, it would be necessary, while maintaining the radially symmetrical design principle, to significantly reduce the diameter of the actuator, this either already being excluded for structural reasons or else requiring much higher magnetic power densities. This, in turn, necessitates particularly valuable (and therefore expensive) materials, for example for the permanent-magnet unit 38, and therefore such miniaturization is not only potentially uneconomical but also results in additional special outlay on logistics for special components.
The object of the present invention is therefore to improve an electromagnetic actuating apparatus of this generic type in respect of simple production and flexibility in use, in particular to improve its suitability for asymmetrical installation conditions (where “asymmetrical” in the scope of the present invention is to be understood as meaning those installation conditions which are not radially symmetrical in relation to a movement direction of the tappet unit).